(1) Field of the Invention
This invention relates to oil wells, and more particularly to the prevention of environmental damage caused by the leakage of well fluid from above the pumping tee of an oil well due to failure of the polished rod liner or stuffing box. Persons engaged in oil well production have ordinary skill in the art.
(2) Description of Related Art
Oil wells often have a pump jack to reciprocate a sucker rod. The sucker rod operates a reciprocating pump at the bottom of the well. Bridle cables are attached to the pump jack. The bridle cables extends to a bridle. A polished rod is connected at the bridle. At the other end of the polished rod, the polished rod is connected to the sucker rod.
The polished rod passes through a stuffing box and into an eduction tube at the well head. Oil and other well fluids are pumped up through the eduction tube. The stuffing box prevents the fluids from flowing out of the eduction tube and onto the ground.
A polished rod liner is used to protect the polished rod. The polished rod liner surrounds the polished rod and is attached by a polished rod liner clamp to the polished rod. The polished rod liner is attached to the polished rod below the bridle. The polished rod liner clamp includes a seal between the polished rod liner and the polished rod. Well fluid will be between the polished rod liner and the polished rod. The polished rod liner is a thin tube of steel that has a particularly smooth outside surface so that a non-leaking, low friction seal is maintained between the polished rod liner and the stuffing box.
The polished rod liner can fail for a number of reasons. Among the reasons for polished rod liner failure are metal fatigue due to the reciprocation of the polished rod, misalignment between the polished rod liner and the stuffing box, and failure due to corrosion of the polished rod liner due to impurities in the produced well fluids. When the polished rod liner fails, well fluid is permitted to flow or spray from the polished rod liner. The result of failure of the polished rod liner is an environmental spill in the area surrounding the well.
The term "oil well" is used in this application to include salt water wells or gas well or any of the fluid pumping well operated by a reciprocating rod which might pollute the environment.